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The only widely proposed screening procedure for skin cancer is visual examination of the skin, including both self-examination and clinical examination.

Benefits

The evidence is inadequate to determine whether visual examination of the skin in asymptomatic individuals leads to a reduction in mortality from melanomatous skin cancer. Further, in asymptomatic populations, the effect of visual skin examination on mortality from nonmelanomatous skin cancers is unknown.

Magnitude of Effect: Unknown.

Study Design: Direct evidence limited to a single ecologic study.

Internal Validity: Poor.

Consistency: N/A.

External Validity: Poor.

Harms

Based on fair, though unquantified evidence, visual examination of the skin in asymptomatic individuals may lead to adverse consequences. These include complications of diagnostic or treatment interventions (such as poor cosmetic or functional outcomes) and the psychological effects of being labeled with a potentially fatal disease. Other harmful consequences are overdiagnosis, leading to the detection of biologically benign disease that would otherwise go undetected, and the possibility of misdiagnosis of a benign lesion as malignant.

Magnitude of Effect: Unknown.

Study Design: Case series, ecologic studies.

Internal Validity: Fair.

Consistency: Fair.

External Validity: Fair.

Description of the Evidence

Incidence and Mortality

There are three main types of skin cancer:

Basal cell carcinoma.

Squamous cell carcinoma (together with basal cell carcinoma, this is referred to as nonmelanoma skin cancer).

Melanoma.

Basal cell carcinoma and squamous cell carcinoma are the most common forms of skin cancer but have substantially better prognoses than the less common, generally more aggressive melanoma.

Nonmelanoma skin cancer is the most commonly occurring cancer in the United States. Its incidence appears to be increasing in some [1] but not all [2] areas of the United States. Overall U.S. incidence rates have likely been increasing for a number of years.[3] At least some of this increase may be attributable to increasing skin cancer awareness and resulting increasing investigation and biopsy of skin lesions. A precise estimate of the total number and incidence rate of nonmelanoma skin cancers is not possible because reporting to cancer registries is not required. However, based on Medicare fee-for-service data extrapolated to the U.S. population, it has been estimated that the total number of persons treated for nonmelanoma skin cancers in 2012 was about 3 million.[4,5] That number would exceed all other cases of cancer estimated by the American Cancer Society for that year, which was about 1.6 million.[6]

Melanoma is a reportable cancer in U.S. cancer registries, so there are more reliable estimates of incidence than is the case with nonmelanoma skin cancers. In 2018, it is estimated that 91,270 individuals in the United States will be diagnosed with melanoma and approximately 9,320 will die of it. The incidence of melanoma has been increasing for at least 30 years; from 2005 to 2014, the incidence rate increased by 3% per year among adults aged 50 years and older; however, data from the same time period indicate that incidence rates stabilized in individuals younger than 50 years.[5] From 2006 to 2015, mortality rates declined by 1% per year in individuals aged 50 years and older and declined by 2.6% per year in individuals younger than 50 years.[5] The long-term rise in incidence rates is caused, at least in part, by screening in clinical settings and self-examination resulting from campaigns to increase skin cancer awareness.

A study of skin biopsy rates in relation to melanoma incidence rates obtained from the Surveillance, Epidemiology, and End Results Program (SEER) of the National Cancer Institute indicated that much of the observed increase in incidence between 1986 and 2001 was confined to local disease and was most likely caused by overdiagnosis as a result of increased skin biopsy rates during this period.[7] A second study that used SEER data between 2002 and 2009 reported similar findings.[8]

The incidence of melanoma has also been increasing in children and adolescents. Between 1998 and 2007, a 2.5% relative yearly incidence increase in melanoma among children and adolescents was observed in SEER databases.[9] During that time, the average annual incidence in this group was exceptionally low (5.4 per 1 million), which may have resulted in spurious trends. Nevertheless, similar trends have been seen in Sweden.[9] In the U.S. study of pediatric melanoma, nearly one-half of the patients had local disease (22% of patients had in situ disease and 25% of patients had superficial spreading), and nearly one-half of the patients had disease with a thickness of less than one millimeter. Given that mortality from pediatric melanoma had been fairly stable during those years,[10] it is likely that the increase in incidence could be explained, at least in part, by overdiagnosis.

Risk Factors

Epidemiologic evidence suggests that exposure to UV radiation and the sensitivity of an individual's skin to UV radiation are risk factors for skin cancer, although the type of exposure (high-intensity and short-duration vs. chronic exposure) and pattern of exposure (continuous vs. intermittent) may differ among the three main types of skin cancer.[11,12,13] In addition, the immune system may play a role in pathogenesis of skin cancers. Organ-transplant recipients receiving immunosuppressive drugs are at elevated risk of skin cancers, particularly squamous cell cancers (SCC). Arsenic exposure also increases the risk of cutaneous SCC.[14,15]

The incidence of melanoma rises rapidly in whites after age 20 years. Fair-skinned individuals exposed to the sun are at higher risk. Individuals with certain types of pigmented lesions (dysplastic or atypical nevi), with several large nondysplastic nevi, with many small nevi, or with moderate freckling have a twofold to threefold increased risk of developing melanoma.[16] Individuals with familial dysplastic nevus syndrome or with several dysplastic or atypical nevi are at high (>fivefold) risk of developing melanoma.[16]

It is important to note that, for the general population, most melanomas may not arise from preexisting nevi; a meta-analysis of studies published between 1948 and 2016 found that the prevalence of nevus-associated melanomas was only 29%, compared with 71% for the prevalence of de novo melanomas.[17]

Accuracy of Making a Clinical Diagnosis of Melanoma

Observer variability among physicians has been noted in the evaluation of skin lesions and subsequent biopsy specimens. A systematic review of 32 studies that compared the accuracy of dermatologists and primary care physicians in making a clinical diagnosis of melanoma concluded that there was no statistically significant difference in accuracy. However, the results were inconclusive, owing to small sample sizes and study design weaknesses.[18]

A study of 187 pathologists who practiced in the United States found that cases of moderately dysplastic nevi to early-stage invasive melanoma had less than 50% agreement, with a reference diagnosis defined by consensus of experienced pathologists.[19] At a U.S. population level, it is estimated that 82.8% (95% confidence interval) of melanocytic skin biopsy diagnoses would be verified if they were reviewed by a consensus reference panel of experienced pathologists.[19] In addition, differentiating between benign and malignant melanocytic tumors during histologic examinations of biopsy specimens has been shown to be inconsistent, even in the hands of experienced dermatopathologists.[20,21] This variability in the diagnosis of melanocytic lesions undermines the results of studies that examine screening effectiveness and also may undermine the effectiveness of any screening intervention. Furthermore, this suggests that requesting a second opinion regarding the pathology of biopsy specimens may be important.[20,21]

Evidence of Benefit Associated With Screening

More than 90% of melanomas that arise in the skin can be recognized with the naked eye. Very often there is a prolonged horizontal growth phase during which time the tumor expands centrifugally beneath the epidermis but does not invade the underlying dermis. This horizontal growth phase may provide lead time for early detection. Melanoma is more easily cured if treated before the onset of the vertical growth phase with its metastatic potential.[22]

The probability of tumor recurrence within 10 years after curative resection is less than 10% with tumors less than 1.4 mm in thickness. For patients with tumors less than 0.76 mm in thickness, the likelihood of recurrence is less than 1% in 10 years.[23]

A systematic review of skin cancer screening examined evidence available through mid-2005 and concluded that direct evidence of improved health outcomes associated with skin cancer screening is lacking.[24] An updated review published in 2016 found limited evidence that skin cancer screening reduces melanoma mortality.[25,26]

No randomized trials evaluating the efficacy of skin cancer screening on mortality have been completed. A population-based trial (using cluster randomization) to determine the effect of skin cancer screening on melanoma mortality was initiated in Queensland, Australia, but lost its funding after the initial pilot phase, and no health outcomes were ever reported.[27]

Two ecological studies have been conducted using data from Germany. The first was a pilot project conducted in 2003 and 2004, in which a skin cancer screening program was implemented in one federal state. Suggestion of a reduction in melanoma mortality with screening led to the establishment of county-wide skin cancer screening programs in 2008.[28] The programs offered a whole-body skin exam once every 2 years for individuals older than 35 years. The second ecological study compared the melanoma mortality experience in Germany with the melanoma mortality experience of subregions of 22 European countries for the years 2000 to 2013, none of which had organized screening programs. After adjustment for potential confounders, Germany and the 22 European regions had similar malignant mortality rates, suggesting no benefit of screening.[29]

Evidence of Harms Associated With Screening

Harms have not been well studied or reported in quantitative terms, but the potential for adverse consequences from skin cancer screening exists. In the SCREEN study, 4.4% of all screened participants underwent a skin excision for a suspicious lesion, but the majority of biopsies did not result in a cancer diagnosis. The detection rate was especially affected by age. One case of melanoma was detected per 28 excisions overall (for both men and women), while 52 skin excisions were required to detect one melanoma in men aged 20 to 34 years.[30]

Visual examination of the skin in asymptomatic individuals may lead to cosmetic or functional complications of diagnostic or treatment interventions and the psychological effects of being labeled with a potentially fatal disease, although robust data on the frequency of such events are lacking. Other harmful consequences are overdiagnosis, leading to the detection of biologically benign disease that would otherwise go undetected,[7,8,31] and the possibility of misdiagnosis of a benign lesion as malignant. (Refer to the Accuracy of Making a Clinical Diagnosis of Melanoma section of this summary for more information.)

Changes to This Summary (07 / 30 / 2018)

The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Description of the Evidence

Added text about two ecological studies conducted using data from Germany; the first was a pilot project conducted in 2003 and 2004, in which a skin cancer screening program was implemented in one federal state, and suggestion of a reduction in melanoma mortality with screening led to the establishment of county-wide skin cancer screening programs in 2008 (cited Katalinic et al. as reference 28). Also added text about the second ecological study that compared the melanoma mortality experience in Germany with the melanoma mortality experience of subregions of 22 European countries for the years 2000 to 2013, none of which had organized screening programs; after adjustment for potential confounders, Germany and the 22 European regions had similar malignant mortality rates, suggesting no benefit of screening (cited Kaiser et al. as reference 29).

This summary is written and maintained by the PDQ Screening and Prevention Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ® - NCI's Comprehensive Cancer Database pages.

About This PDQ Summary

Purpose of This Summary

This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about skin cancer screening. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.

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Levels of Evidence

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